Apparatus for forming tubular l&#39;s



C. F. SEIBERT APPARATUS FOR FORMING TUBULAR LS Sept. 30, 1952 s sheets-skeet. 1

Filed Aug. 31, 1946 INVENTOR. CARL ESE/BERT BY l ATTO EY P 30, 1952 c. F. SEIBERT 2,612,205

APPARATUS FOR FORMING TUBULAR LS Filed Aug. 51, 1946 5 Sheets-Sheet- 2 V l I O Z6 Z6 0 y s INVENTOR.

6ARL F 32/55/27 ATTORNEY Sept. 30, 1952 c. F. SEIBERT I 2,612,205

, APPARATUS FOR FORMING TUBULAR LS Filed Aug. 31, 1946 s Sheets-Sheet 5 INVENTOR. CARL Ff 55/5597 A TTORNEY Patented Sept. 30, 1952 APPARATUS FOR- FORMING TUBULAR LS Carl Frederick Seibert, Bradford, Pa., assignor to Dresser Industries, Inc., Cleveland, Ohio a corporation of Pennsylvania Application August 31, 1946, Serial No. 694,351

Claims. (01. 153-'-48) The present invention relates to the manufacture of tubular Ls, the term L being used generically to comprise not only ninety degree turns, but also turns of other angles greater or less than ninety degrees. The invention is particularly adaptable to the forming of tubular Ls of relatively short radius, for example, Ls having a center line radius not more than about twice the nominal diameter of the pipe or tube.

Various methods have been heretofore utilized to bend suitable lengths of tubing into L s, among which is a method and apparatus for forming tubular Ls disclosed in a copending application for Letters Patent, Serial No. 593,931, filed May 15, 1945, by Clyde J. Martin, now Patent No. 2,528,315, granted October 31, 1950/ In that application an internal flexible mandrel is positioned in a blank to support, mold and shape the internal surface of the blank while the external surface of the blank is being subjected to the action of opposed dies in the forming of the blank into a tubular L. In making Ls by this method it has been found that malformation of the Lfs and die breakage has, in'some instances, occurred. These troubles appear to have been caused by improper initial positioning of the blanks, mandrel, or both, in the dies, and, in the failure of the blanks, mandrel or both to be maintained in proper position during the forming operation.

An object of the invention is to provide centering means for accurately positioning the blank in an apparatus for forming tubular Ls from a straight blank.

'Another object of the invention is to provide means for maintaining the blank in proper position during the forming of the blank into a tubular L.

A further object of the invention is to provide means for maintaining a flexible mandrel in cor rect position within a blank during the forming of the blank into a tubular L.

'A still further object of the invention is to provide an improved method of, and apparatus for, forming and finishing a tubular L between opposed die sections.

The present invention aims to overcome the foregoing difiiculties and accomplish the foregoing objects by providing an apparatus for initially centering the blank and mandrel in proper position between the opposed dies and for maintaining the blank and mandrel in proper position during the forming operation. The invention further provides a method and apparatus for simultaneously forming a blank and for sizing or finishing another blank.

In accordance with the invention the initial centering of the blank is accomplished by providing lateral grooves adjacent the ends of the cavity of the concave die. The grooves are spaced by a distance equal to the length of the straight blank. The blank, to be formed into an L, "is positioned in the die, the grooves assuring that the blank is properly centered, and is maintained in centered position. As the I blank is being formed into the desired shape, the straightkline distance between the ends of the blank gradually becomes shorter and the blank is then forced'into another set of grooves between'the initial'centering grooves. The blank is thus maintained in a properly centered position during the entire forming operation.

The centering of the mandrel is accomplished by providing curved guide members adjacent'the ends of the cavity of the convex die and movable therewith. The mandrelis provided with projecting ends which are guided in the desired path. As the opposed dies approach together'the ma'ndrel is initially correctly positioned, and as the bending operation proceeds the curvature of the guideway is such as tomaintain the mandrel'in proper position during the entire forming operation. Y

The particular advantage of themethod' in accordance with the invention is that, malformation of the L and breakage of the die are practically eliminated. In addition the forming operation maybe performed more rapidly than by previous methods even though the operation is performed by 'operators' of low skill. f

In accordance withthe inventionthe simultaneous forming of one blank and-the finishingof a second blank are accomplished by providingopposed dies having composite die cavities. Oneset of die cavities forms the straight blankinto a curved blank of the desired curvature. The-other set of die cavities finishes the curvedblankto the desired size and smoothes out any irregularities in the blank which may have beenv caused during the forming operation; I v

The particular advantage of this apparatus-is that it permits greater speed in the manufacture of the Ls. Labor, time, and equipment. are

' saved as a forming operation and a finishingoperation are performed simultaneouslyby a single set of dies and in a single press. Moreover, no storage facilities or transportation facilities for the partially formed Ls are required as the formed L is merely transferred from the forming die cavity to the adjacent finishing die cavity :for the finishing operation. By this method-the Hchance of unfinished =Ls being'suppiied is minimized as the finishing operation is performed immediately after the forming operation.

Apparatus for carrying out the method of the invention is illustrated in the accompanying drawings. It will be understood-that this embodiment of the invention is shown merely by way offlexamplb.v and-that the invention 'is in no way limited to the use of the specific apparatus illustrated.

In the drawings,

Fig. 1 is an elevational. viewoindoperatin forming dies showing blank and mandrel positioning means, in accordance with the invention, a formed tubular L being shown in. position the closed die and a mandrel being shown in p sition in the blank.

Fig. 2 is an end view partly in section and partly in elevation, showing the composite dies, for form-- ing and finishing the L s.

- 3.1s aplan view of thelower section of the composite die showing the-two die cavities.

Fig. sis a. plan-view of the upper section of the composite die.

Elsi. is a longitudinal sectional view of a straight blank with a mandrel therein positioned v 1 a composite die I, comprised of upper die section 2 and lower die section 3. A flexible mandrel 4. is shown. in position in a formed L 5 whichhas been shapedinto the desired curvature 1mm a-straight cylindrical blank by theaction .ottheopp s d dissections and the mandrel.

The upper die section 2 is provided on its face ,eveith a-forming die cavity 8a and a, finishing die navity 9c. (The forming die cavity corersponds generallyinshape to the, inner half of the tubular ,'L,;5;, ji;., e., thethalf' on the inner side of the'bend .ZQI' curvature of the L. The forming die cavity 8a is arcuate when viewed in a vertical section wthronsh.rthe; -loneitudinal center line or the L shown in Fi s. land '2. The. cavity is strai ht as; viewed in. arsectionxat right angles I "to thevertical section through .the longitudinal center line of the, L 5.. The finishing die cavity :correspondsgenerally in shape to. ahalf of the finished L,".i. .-e., "the half on one side of the cavity corresponds generally in contour to the outer half of the exterior surface of the L, i. e., the half on the outer side of the bend or curvature of the L. The die cavity 8?), like cavity 8a, is arcuate when viewed in a vertical section through the longitudinal center line of the L 5,.andisstraight as viewed in a section at right angles to this vertical section and through the longitudinal center line of the L. The lower die section also has a finishing die cavity 9b which is ,..located.adjacent the forming die cavity and posiplane through the radius of curvature of the L, and is located adjacent, and positioned approximately at right angles to the longitudinal :axis of the forming die cavity. The finishing die cavity 9a isacruate as viewed in the horizontal section taken through the longitudinal center line of the L 5 and straight if viewed in a vertical section through the longitudinal center line at right angles to the horizontal section. For convenience of manufacture, the die section 2 is made up of a plurality of parts and elements removably secured to a base portion [0 bymachine one another.

' The lower die section-31s providedwith a formring die cavity 8b and a finishing die cavity 9b, Fwhichyare formed from separate die blocks and 'attached to a base portion. The forming die tioned approximately at right angles to the longitudinal. axis. of the forming die cavity. The finishing die. cavity 9b, like the cavity 90. is

arcuate as-viewed; in a horizontal section through the longitudinal center line of the L 5, and straight if viewed in a vertical section through the illongitudinal center line. The lower die section 3 like the upper die section 2 is shown as being made up of a plurality of parts orelements which are :removably and. interchangeably. se-

- cured to. a baseportion l2, for example, bysuitable bolts. or machine screws 13..

It will be seen that when the composite. die I is closed, the die cavities 8a and. 8b. cooperate to form they die cavity 8 corresponding approximately to the desired shape of the. formed L. The die-cavities 9a and 9b cooperatetoform the die cavity 9, which .is shaped to more accurately form the L.to the desired shape.

It may be necessary in some instances, par- .ticularly when forming Ls from resilient material, to perform more work on the L in thefinishing operation. This may be accomplished by forming the finishing die cavity 9 with a generally ellipticalshape. The cross sections of cavities 9a and 31)- will. then be semi-elliptical in shape, the minor axis of the ellipse being in .a vertical plane so that the walls of the partly formed L all may be worked beyond the yield pointer the material; in the finishing operation. Suitable means is. provided for moving the u per and lower die sections 2 and 3 toward and away from one another. to open and close the die, for example; the die sections may be mounted on opposed members of a suitable hydraulic or other press.

The, flexible mandrel 4, which cooperates with the die sections 2 and 3 in forming the blank to the desired, shape. comprises a plurality of sections which are pivoted relative to one another to form an articulate and flexible structure. The mandrel conforms to the inner surface of the blank, and bends with the blank as it bein formedby the die sections affording substantially continuous internal support to the blank throughout its extent, or at least throughout the portion acted on by the die and cooperating with the die to form the blank to the desired shape. The mandrel comprises a plurality of spaced end sections 16 and. I7 and an intermediate central section I8. The end sections 16 and I! are substantially straight, the surfaces of said sections being approximately cylindrical. The diameter of the end sections [6 and I1 is approximately equal to the inside diameter of the tubular blank so that the mandrel will fit into the blank snugly but with sufficient clearance to prevent binding. The intermediate section IB is arcuate or curved'longitudinally, the surface correspondi'ng to the shape of the form L. The ends of the arcuate central section I8 are cut off at the angle l'9- thus forming approximately V-shaped ends which are received in V-shaped recesses 20 provided in the adjacent ends of the sections [6 and I1. i'll'ieinter-flttingportion ofthe respective sections' of the'inandrel serve as pivotal connections between the sections which are thus maintained in proper operative position relative to one another during the forming operation. To facilitate removal of the mandrel from-the L after the latter has been formed the central section l8 may be split lengthwise, for example,

along theplane of the longitudinal curvature of the section or at a slight angle thereto as indicat- The end'sections of the mandrel are preferably formed with lugs or cars 22 and 23 for a purpose to be described later.

In accordance with the invention,'centering or zontalplane. The grooves may taper from a 'maximum depth at the center of the cross section'of the die cavity to a minimum depth at the surface of the die member. The'grooves are spaced apart at distances corresponding to the length of the straight tubular blank. The straight outer sides of the grooves prevent movement of the blank out of the die cavity during the forming operation, while the fiat bottoms of the grooves allow'the ends of the blank to slide inwardlyinto the die cavity during the course of the forming operation. A further set of trans- -verse grooves 21 is positioned inwardly from the initial positioning grooves 26 and serve to position the blank duringthe latter part of the forming operation. These grooves are likewise generally L'-shaped in cross section, and, like the initial centering grooves 26, may taper from a max- "imum depth at the center of the cross section of the die cavity to a minimum depth at the surface of the die member, so as to be crescent-shaped in elevationlFigure 3). i

' The centering of the mandrel is accomplished in accordance with the invention by providing curved guide members 28 which maybe afiixed to an extension 29 ofupper die section 2, for example-by means of bolts or screws 30. The'guide 'members 28 have surfaces 3| which flare outwardly at the bottom thereof, and are adapted to guide ends 22 and 23 of mandrel 4 into a correctly'centeredposition before the upper diesection 2 has contacted the blank. Other guide surfaces 32 are provided to guide the mandrel during the forming operation. The shape of theguide surfaces is such as to correspond with the path taken by the ends 22 and 23 of mandrel 4 during the forming operation. It is not essential that the guide surfaces 32 be in actual contact with the ends of the mandrel excepting in case one or both of the ends of the mandrelshould be out of position. In other words, if the mandrel is positioned perfectly centrally of theblank, with the mandrel ends in proper relation to the center, there may .be' a slight clearance between each of the outer portions of the end sections 22 and 23 and the guide surfaces 32, the clearance being an amount representing the maximum allowable shifts of either of the ends sections of the mandrel during the forming operation.

In forming a tubular L with the apparatus shown-in Figs. 1 to 4, a straight blank of tubular stock"6 is positioned in the open forming die 8 "with its endsin the centering "grooves 26.- The modifications and variations.

mandrel 4 has been placed in the blankB' with the straight side of the central sectionof the mandrel up, while the arcuate side is down. The opposed die sections are then broughttogeth'er by suitable means such as a press, the direction of the force applied to the blank by the dies being in the plane of curvatureof the desired L. The formed L is shown in the die sections in Fig; 1. i

The operation of the dies, mandrel, blank centering means and mandrel guiding mean is illustrated more fully in Figs. 5 through 9 which show representative positions of these parts during the forming of the L. In Fig. 5 the straight blank 6 is shown in position in the grooves 28. with mandrel 4 in place in the blank. There is a. slight clearance between guiding surfaces 3| of guiding members 28 and the ends 22 and 23 ofmandrel 4.. The grooves and guiding surfaces have cooperated to properly center the mandrel and blank within the die cavity. The grooves have centered the blank with respect to the dies. The guiding surfaces have centered the mandrel both with respect to the blank and with respect to the dies. Although Figs. 6 through 9 show only one end of the blank and dies, it is understood that the action of the blank and dies at the other endis similar. In Fig. 6 the dies have started to bend blank 6, the ends of the blank starting to leave centering grooves 26. The vertical side wall of the L-shaped groove 26 has prevented the end of blank 6 from slipping endwise out of centered positionin die cavity 8a, while the surface 32 of guiding member 28 has prevented the end-22 of mandrel 4 from shifting from its centered position in blank. 6. In Fig. 8 the end ofthe blank has moved into groove 21. In Fig.- 9 the forming operation is practically completed, the end of blank 6 remaining in groove 21. It will be noted that during the bending operation the end sections [6 and ll of mandrel 5 have pivoted about the center section [8 aiding the opposed die sections 2 and 3 in molding andshaping the internal surface of the blank while supporting the walls of the blank against collapse, wrinkling or bulging.

The formed L, after being partiallyshapedby the forming portion of die sections 2 and 3, is r0.- tated about ninety degrees and placed in the adjacent finishing portion of the die sections and another straight blank is placed in the forming portion of the die sections. The die sections-are again brought toward one another finishing the formed L 5 into a more accurately formed L, and

simultaneously forming another straight blank into a formed L, the direction of the force'applied by the dies to the formed L being perpendicular -to the plane of the bend, while the force applied to the straight blank is in the bend. v

While certain forms of apparatus forcarrying out my invention have been shown in the drawings and particularly described, it will be understood that the invention is in no way limited to this specific apparatus or to the particular steps described, but is subject to various For example, a greater number of grooves may be employed, each set of grooves acting during a-portion of the forming operation. The invention is equally applicable to the forming of tubular Lfs of circular or other cross section. Although for convenience in nomenclature, certain dies have-been referred to as upper,.-and other as lower dies, the position of the dies can be reversed,orthe dies plane of the'desired aerazzos '7 Herzturn'e'diatz-anyfdesiredz.angle; 'StilLother rembodimentsaiand; variations of; the; invention Wi-thin; the scope; off the appendedzclaims; will; be

obvicustoperscns ski-lled'in theeart.v

What; L claimszand desire. to: secureabyLetters -Batent';is;:

1.1-1112. apparatus-,1 forrforming a tubular L .from blank: of tubular stock; the combination of." a flexible mandrel insertable in the blank, themanedre1 having. endszproiecting: beyond: the ends of the; blank; opposed die; members; having cooperating concaveandconvexdie navitiesxcorrespondingLin; contour-to: the iiormed .L, means; retaining theiblan-kih; position. formed in.the. cavity of. the concave; die, member, and; mandrel. positioning 111183135.. movable. with. .the-izconvex... dice. member :adapted; tc .operatively engage: the; ends .of; the

.ima' ndrel.v

2:..1111; apparatus for; fonninga. tubularsL. from :azblank; of;;tubular: stock; the combination. of, .a flexible; mandrel havingends projecting: beyond the; ends-pf? thablanl'c; opposedv die .membershavcooperating concave and? convex; (116?. cavities corresponding-t contour? to. the. formed;' 1.2,. the :concave: die;v member having: a" pair.- of; spaced transverse positioning groove-s formed inthe: die "cavity eachzadjacentan end thereof adaptedxto receive and: longitudinally hold the blankin posi- 'tion. in the concaverdiermemb'er; and mandrel positioning. means: movable with: the. convex: die member; adapted :to: up eratively engage. the; ends jcntheman-drel.

v 3; In.apparatnssforiiorming'.a tubular-5L, from a blanklziofztubularstock; thexcombinationnof; a fiexbile mandrelihaving; ends. projecting-beyond vtlrieiend'ssofrthe:blank, opposed die members havingicooperating. concave and;convex die cavities corresponding;inicontour tothe formed L, the concavezfidie member having a pair of; spaced transverse .positioning'grooves formed in the die cavity each adjacent' an end thereof adapted to i'receiverand longitudinally'hold the blankin positiomin the concavedie'member, a second pair of transverse grooves formed in theconcave die cavity between thefirst. pair of grooves, the second pair of grooves being positioned to receive thezends. of .theablankafter the formingoperation hascaused' the ends: of. the 'blank'to travel .inward'l'y towards ,the. center: of j the cavity" of. the concave die member; and mandrel positioning meansxmovable; with the convex die member adapted to operatively engage the ends of: the 'mandreli.

.4.-In apparatus fonforming a tubular L from a blanksof tubular stock,- the combination.v of a fiexibletmandrel insertable inside theblank, the mandrel having ends projecting beyond the ends of the blank; opposed die members having cooperating'concaveand convex die cavities corresponding in contour to the formed L, means retaining the blank in position formed in the "cavity of the concavedie member, and mandrel r positioning :means: comprised of guiding members arrangedto move With'the convex die member, theiguiding surfacesofthemembers being con- "tinuous smooth' surfaces shaped to. conformto thezdesired path of. the ends of themandrelidur- 'ingJthe forming operation and to preventdevia- 'tiomof i the ends-of i the mandrel fromsaid desired path.

5'.1.In:apparatusi for: forming a tubular; L .from -arblankmf tubular'stock; the combinaticnof' 'a ,flexibleirmandrel. insertablein. the. blank, the mandrelzhaving: endsprojecting beyond thewends O'ff'th'; blank; opposed die members having ooone-rating; concaveand. convex. die-.-..cav1ties corresponding; in.- contour to the.- formed. L.. means retaining the: blank; imposition formed. in; ..the

cavity of; the; concave; die. member, and mandrel positioning; means: comprisedv or guiding .menrberstarranged to. move with thee-convex diememher; the; guiding surfaces-.01 the members being positionedand; shaped to guide the ends 'oiithe mandrel into the desired; path before the convexsurfaceofthe die member c0ntacts.the.-.b1ank and; to. maintain therendsiofi the mandrel in the desired. path during the iormingoperatiom 6. In apparatus-forriiormingia tubular L.. from a: blank of tubular stock; the. combinationof a flexible; mandrel insertable in the blank;. the mandrel. having endsprcjecting; beyond the ends of. the. blank,uopposed.. die.- members. hav n copositioned. between the first pair -of-grooves the second pair of. grooves being positioned to. receive the ends of. the blank after the forming operation has caused the ends of the blank. to travel. inwardlytowards thev center of. the cavity ofv the" concave die member, and mandrel positioning means comprised of guiding members arranged: to move, with the convex .die member, theguidingzsurfaces of themembersbeingpositioned and: shaped to guide theends of themandrel into the; desired position beforethe convexsurface of thedie member contacts the blank: and. to). maintain. the ends of the. mandrel in: the desired path during the forming operation.

7.. Inapparatusfor forming'a tubular L from a blank of tubular stock, the combination of a flexible'mandrel insertable in the-blank; opposed die members having cooperating concave and convexdie cavitiesv corresponding in contour to the; formed L, means for centering theblank relative to. the die cavities comprising, a pair; of transverse positioning grooves. in. the wall; of the concave die. cavity spaced. aparta distance-equal to thelengthcof saidblank; and.means for centering said mandrelrelative to. said diescavity andblank;

8; In apparatusifbrforminga tubulariL from a blankioftubular'stock the; combination of; a flexib-le mandrelinsertable intheblank; opposed die members-having cooperating concave and convex dieg cavities" corresponding: in. contour to the iormed L, the concave-die member having a first pair of spaced transverse positioning grooves formed inthe concave die cavity each adjacent anendofthe cavity; thereof so constructediand arranged as to receive and longitudinally hold the blank: in position. in the concave die member, 'a second pair of transverse grooves formed in the concave. die cavity positioned between the first pairof grooves-,the second pair of grooves being positioned to. receive: the ends of the'blanktafter the formingxoperationthas caused the ends of the blank; to travel inwardly towards the. centerwof thecavity' of the .concave die, member, and means for centering said mandrel; relative.v to; said die cavities; and; blank;

9; In apparatus-fonrforming:a tubularrL .from'la blank; of; straight; tubular .stock, the, combination dfz? a1: flexible: mandrel; insert-able; in: prede- 9 termined position in the blank and opposed die members having cooperating concave and convex die cavities corresponding in contour to the formed L, the concave die member having a first pair of opposed spaced transverse positioning rooves formed in the concave die member adjacent the opposite ends of the die cavity and so constructed and arranged as to receive the blank and hold it in position in relation to the cavity and a second pair of transverse grooves formed in the concave die cavity at points spaced inwardly from the first grooves, the second pair of grooves being positioned to receive the ends of the blank after the forming operation has caused the ends of the blank to travel inwardly towards thecenter of the cavity of the concave die member and to reposition the blank relative to the die members in the event it has become off center during said travel.

10. In apparatus for forming a tubular L from a blank of tubular stock, the combination of opposed die members having cooperating concave and convex die cavities corresponding in contour to the formed L and movable toward one another in a direction approximately radial to the curvature of the formed L, abutments engaging the ends of a blank to retain the blank in predetermined lengthwise position relative to said die cavities, an articulated mandrel insertable in the blank and comprising a plurality of sections including a rigid section having on one side a curved surface conforming to the shape of the formed L and on the opposite side a substantially cylindrical surface, said mandrel cooperating with the concave die cavity to press the blank into predetermined shape and means for guiding the opp 10 site ends of the mandrel in converging curved paths to maintain said mandrel centered relative to said die cavities and blank during the forming operation.

CARL FREDERICK SEIBERT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 251,003 Vanstone Dec. 13, 1881 406,992 Burgoin July 16, 1889 563,797 Peters July 14, 1896 689,609 Einfeldt Dec. 24, 1901 858,847 Connors June 11, 1907 953,253 Brinkman -1 Mar. 29, 1910 1,136,364 Powell Apr. 20, 1915 1,225,708 Dies May 15, 1917 1,849,054 Boissou Mar. 15, 1932 1,875,954 Taylor Sept. 6, 1932 1,942,353 Berger Jan. 2, 193 2,041,428 Milligan May 19, 1936 2,044,322 Oliver et a1. June 16, 1936 2,285,275 Harder June 2, 1942 2,295,852 Le Jeune Sept. 15, 1942 2,528,315 Martin Oct. 31, 1950 FOREIGN PATENTS Number Country Date 17,728 Great Britain 1891 59,706 Switzerland Nov. 9, 1912 195,278 Great Britain Mar. 29, 1933 

